#mainContent .common {
	position: absolute;
	width: 100%;
	height: 100%;
}

#mainContent .common #menu {
	width: 100%;
	height: 100%;
}

#mainContent .common #menu #back {
	background-color: black;
	width: 100px;
	height: 30px;
	left: 5%;
	top: 5%;
	font-size: 15px;
	text-align: center;
}